Bioenergertics

Question 1

What is the photosynthesis equation?

Answer 1

carbon dioxide + water =
glucose + oxygen

Question 2

What type of reaction is photosynthesis ? Explain why?

Answer 2

photosynthesis as an
endothermic reaction in which energy is transferred from the environment to the chloroplasts by light

Question 3

How does temperature effect the rate of photosynthesis?

Answer 3

Plants can photosynthesise over a wide range of temperatures from 0°C to around 50°C.

The optimum temperature for most plants is 15°C to around 40°C.

Temperature affects the rate of photosynthesis in crop plants and affects where certain crops can be grown.

Question 4

How does light intensity effect the rate of photosynthesis?

Answer 4

Without enough light, a plant cannot photosynthesise very quickly - even if there is plenty of water and carbon dioxide.

Increasing the light intensity increases the rate of photosynthesis, until some other factor - a limiting factor - becomes in short supply.

Question 5

How does carbon dioxide concentration effect the rate of photosynthesis?

Answer 5

Carbon dioxide – with water – is one of the reactants in photosynthesis.

If the concentration of carbon dioxide is increased, the rate of photosynthesis will therefore increase.

Again, at some point, a factor may become limiting.

Question 6

How does the amount of chlorophyll effect the rate of photosynthesis?

Answer 6

Chlorophyll absorbs the light energy required to convert carbon dioxide and water into glucose.

Chlorophyll is green - so absorbs the red and blue parts of the electromagnetic spectrum and reflects the green part of the spectrum. Leaves with more chlorophyll are better able to absorb the light required for photosynthesis.

Question 7

What is the glucose produced in photosynthesis used for?

Answer 7

• used for respiration
• converted into insoluble starch for storage
• used to produce fat or oil for storage
• used to produce cellulose, which strengthens the cell wall
• used to produce amino acids for protein synthesis.
  To produce proteins, plants also use nitrate ions that are absorbed
  from the soil

Question 8

What is respiration?

Answer 8

Respiration in cells can take place aerobically (using oxygen) or anaerobically (without oxygen), to transfer energy.

Question 9

What do organism need energy for?

Answer 9

• chemical reactions to build larger molecules
• movement
• keeping warm.

Question 10

What is the equation of Aerobic respiration?

Answer 10

glucose + oxygen = carbon dioxide + water

Question 11

What is the equation for Anaerobic respiration in muscles?

Answer 11

glucose = lactic acid

Question 12

Why is less energy transferred in anaerobic respiration?

Answer 12

As the oxidation of glucose is incomplete in anaerobic respiration much less energy is transferred than in aerobic respiration.

Question 13

What is the equation for anaerobic respiration in plant and yeast cells ?

Answer 13

glucose = ethanol + carbon dioxide

Question 14

What is fermentation and what is it used for?

Answer 14

Anaerobic respiration in yeast cells is called fermentation and has economic importance in the manufacture of bread and alcoholic drinks.

Question 15

What happens when humans do exercise?

Answer 15

During exercise the human body reacts to the increased demand for energy.
The heart rate, breathing rate and breath volume increase during exercise to supply the muscles with more oxygenated blood.

Question 16

How does anaerobic respiration take place?

Answer 16

If insufficient oxygen is supplied anaerobic respiration takes place in
muscles. The incomplete oxidation of glucose causes a build up of lactic acid and creates an oxygen debt. During long periods of
vigorous activity muscles become fatigued and stop contracting efficiently.

Question 17

What is oxygen debt?

Answer 17

Oxygen debt is the amount of extra oxygen the body needs after exercise to
react with the accumulated lactic acid and remove it from the cells.

Question 18

How is lactic acid converted back into glucose?

Answer 18

Blood flowing through the muscles transports the lactic
acid to the liver where it is converted back into glucose.

Question 19

What is metabolism?

Answer 19

Metabolism is the sum of all the reactions in a cell or the body. The energy transferred by respiration in cells is used by the organism for the continual enzyme controlled processes of metabolism that synthesise new molecules.

Question 20

What does Metabolism include?

Answer 20

• conversion of glucose to starch, glycogen and cellulose
• the formation of lipid molecules from a molecule of glycerol
  and three molecules of fatty acids
• the use of glucose and nitrate ions to form amino acids which in turn are used to synthesise proteins
• respiration
• breakdown of excess proteins to form urea for excretion.